Stroke Alert: A Review of Current Clinical Stroke Literature
By Matthew E. Fink, MD, Professor and Chairman, Department of Neurology, Weill Cornell Medical College,and Neurologist-in-Chief, New York Presbyterian Hospital
Thromboembolic Complications of Pregnancy, Including Stroke, May Persist For Up to 12 Weeks Postpartum
Source: Kamel H, et al. Risk of a thrombotic event after the 6-week postpartum period. N Engl J Med 2014; Feb 13. Online DOI: 10.1056/NEJMoa1311485.
The postpartum state in healthy women is associ-
ated with a variety of thromboembolic complications, including ischemic stroke. During pregnancy, all of the intrinsic clotting factors increase to a maximum around the time of delivery, and then gradually decline to normal by about 6 weeks postpartum. Based on that information, it was believed that the risk of thromboembolism would persist up to 6 weeks postpartum. But little epidemiological evidence existed to confirm or dispute this hypothesis.
Kamel et al used a claims database on all discharges from nonfederal emergency departments and acute care hospitals in California, and identified women who were hospitalized for labor and delivery between January 1, 2005, and June 30, 2010. In addition, they tabulated a composite primary outcome of ischemic stroke, acute myocardial infarction, or venous thromboembolism in those same women. They then used logistic regression to assess each patient's likelihood of a first thrombotic event during sequential 6-week periods after delivery, as compared with the corresponding 6-week period 1 year later.
Among the 1,687,930 women with a delivery, 1015 had a thrombotic event (248 cases of stroke, 47 cases of myocardial infarction, and 720 cases of venous thromboembolism) in the period of 1 year plus up to 24 weeks after delivery. The risk of primary thrombotic events was markedly higher within 6 weeks after delivery than in the same period 1 year later, with 411 events vs 38 events, for an absolute risk difference of 22.1 events (95% confidence interval [CI], 19.6-24.6) per 100,000 deliveries and an odds ratio of 10.8 (95% CI, 7.8-15.1). There was also a significant increase in risk during the period of 7 to 12 weeks after delivery as compared with the same period 1 year later, with 95 vs 44 events, for an absolute risk difference of 3.0 events (95% CI, 1.6-4.5) per 100,000 deliveries and an odds ratio of 2.2 (95% CI, 1.5-3.1). Risks of thrombotic events were not significantly increased beyond the first 12 weeks after delivery. Further prospective study is indicated to identify the mechanisms of these complications and develop preventive strategies.
Stroke After an Episode of Transient Global Amnesia Is Rare
Source: Mangla A, et al. Transient global amnesia and the risk of stroke. Stroke 2014;45:389-393.
Transient global amnesia (tga) is a common disorder that often generates great anxiety in both patient and physician because of its similarity to the symptoms of ischemic stroke. The mechanism of TGA has been hotly debated and attributed to transient ischemia, migraine, and epileptic seizure, but the cause and pathophysiology have never been definitively proven.
The authors searched a California hospital claims database to determine the risk of stroke following an episode of TGA, and compared this to the risk of stroke following migraine, transient ischemic attack (TIA), and an epileptic seizure. After an episode of TGA, the cumulative 1-year rate of stroke was 0.54% (95% confidence interval [CI], 0.36-0.81), after migraine was 0.22% (95% CI, 0.20-0.25), after seizure was 0.90% (95% CI, 0.83-0.97), and after TIA was 4.72% (95% CI, 4.60-4.85). After adjustment for demographic characteristics and stroke risk factors, TGA was not associated with stroke risk when compared with migraine (HR, 0.82). The risk of stroke after TGA was lower than after an epileptic seizure (hazard ratio [HR], 0.57) or after a TIA (HR, 0.27). The natural history of TGA suggests a migrainous mechanism and stroke risk that is similar to that following a migraine.